The Tagetes genus is a member of the family Asteraceae, alternatively known as Compositae, and comprises some thirty species of strongly scented annual or perennial herbs. Tagetes are native from Arizona and New Mexico to Argentina (Hortus Third A Concise Dictionary of Plants Cultivated in the United States and Canada, Macmillan Publishing Company (1976)). Cultivated genera include Tagetes erecta commonly referred to as African marigold, Tagetes patula or the French marigold, Tagetes erecta x patula also known as the triploid marigolds, and Tagetes tenuifolia also known as Tagetes signata and signet marigold. Cultivated marigolds possess showy flowers and are useful for bedding, pots and cutting purposes (Ball Red Book, 15th edition, George J. Ball Publishing (1991)).
In addition to having ornamental value, the genus is recognized as a source for natural color, essential oils and thiophenes, which have nematicide properties. The pigmentation efficiency of marigold is of value in the poultry industry. Dried marigold petals and marigold petal concentrates are used as poultry feed additives to intensify the yellow color of egg yolks and broiler skin (R. Piccalia, M. Marotti, and S. Grandi, Industrial Crops and Products, 8:45-51 (1998)). The carotenoids desired in poultry tissues are a function of their dietary concentration, because poultry do not have the ability to synthesize carotenoids de novo. (D. Balnave and J. N. Bird, Asian-Australiasian Journal of Animal Sciences, 9 (5): 515-517 (1996)). The pigmenting ability of marigold petal meal resides largely in the carotenoid fraction known as the xanthophylls, primarily lutein esters (R. Piccalia, M. Marotti, and S. Grandi, Industrial Crops and Products, 8:45-51 (1998)).
For the feed additive industry, marigolds are produced primarily in Mexico, Peru, Africa, India, China and Thailand. ‘Orangeade’, commercially available from Pan American Seed Company, 622 Town Road, West Chicago, Ill. 60185, was one of the original xanthophyll varieties. Commercial improvements of ‘Orangeade’ include ‘Deep Orangeade’ and ‘Scarletade’. ‘Deep Orangeade’ has lower flower yield than ‘Orangeade’, but greater than ‘Scarletade’. ‘Deep Orangeade’ has greater xanthophyll production per hectare than ‘Orangeade’ due to more double flowers, but has reduced xanthophyll concentrations compared to ‘Scarletade’. Current varieties used for xanthophyll production are open-pollinated and are either semi-double or segregate for fully-double flowers. Marigold hybrid 50011 of the present invention is the first fully-double commercial xanthophyll hybrid. Marigold 50011 has larger flowers and more vigor than ‘Scarletade’, yielding more grams of xanthophyll pigment per hectar. Future variety improvements beneficial for the feed additive industry include increased xanthophyll concentration, disease tolerance, improved vigor as well as the development of varieties that can be produced under different day lengths.
Both genetics and nutrition have been shown to effect marigold flower production. A report on the inheritance of quantitative traits of African marigold, identified that dominance and epistasis, the interaction between two non-allelic genes, had a major role in the inheritance of days for first flowering and flower weight. Additive gene effects and epistasis were found to be more predominant in inheritance of seasonal flower number (B. Singh and V. Swarp, Indian Journal of Genetics & Plant Breeding, 33(2):172-175 (1973)). In a nutritional study, increased nitrogen and phosphorus, both tested to levels of 90 kg/hectare, were shown to increase the yield of flowers and reduce the time to flower (K. Anuradha et al., Indian Journal of Horticulture, 47(3): 353-357 (1990)).